1. Field
Aspects of the present invention generally relate to a sheet processing apparatus for making a photo album or a photo book by binding printed sheets.
2. Description of the Related Art
Japanese Patent Laid-Open No. 9-123636 describes a method of making a photo album by binding printed sheets. In this method, a printed sheet and a small piece of sheet, which is used as a binding margin, are prepared; and a sheet is made by joining the printed sheet and the small piece together by affixing laminate films from both sides in a state in which a gap is formed between the printed sheet and the small piece. A photo album is made by fastening the binding margins of such sheets together. A viewer can easily turn a page of the photo album because a part of the laminate films at the gap, which is at the center of double-spread pages, serves as a flexible hinge.
In the method described in Japanese Patent Laid-Open No. 9-123636, first, upper and lower portions of the small piece and the printed sheet are fixed to each other by using auxiliary sheets, such adhesive tapes, so as to form an appropriate gap between the small piece and the printed sheet. This operation is manually performed by an operator. The operator's power of concentration decreases as the number of sheets increases, and it becomes more likely that quality deviation occurs.
The term “quality deviation” refers to nonuniformity in the dimensions of the gap and nonuniformity in the parallelism between the edges of the gap. FIG. 16A illustrates an example in which a small piece and a printed sheet are fixed to each other by using an adhesive tape in a state in which the printed sheet is inclined relative to the small piece, a portion of a finished sheet that serves as a hinge, which is made by cutting this sheet, has a wedge shape illustrated in FIG. 16B, instead of a parallel shape (a rectangular shape having a constant width). If a photo album is made by binding such sheets, the right page does not have an accurately rectangular shape when the photo album is opened as illustrated in FIG. 16C. Moreover, an upper portion of the hinge on the right page is exposed to the outside to a larger degree than a lower portion of the hinge (as shown by hatching in FIG. 16C). Such poor finish is not pleasing to a viewer's eye, and the appearance of the photo album is impaired. In addition, because such wedge-shaped hinges do not bend uniformly when a viewer turns pages, the viewer feels an unpleasant sensation when turning the pages. Even in a case where the gap does not have a wedge shape but has a parallel shape, the widths of the hinges are not uniform if the dimensions of the gaps differ between the pages, and, also in this case, the finish of the photo album is poor.